A device is provided for sealing an inner tube and an outer tube without excessively deforming the tubes. The device includes two ferrules which cooperate to form a vacuum-tight seal between the inner tube and outer tube and having mating surfaces such that overtightening is not possible.

A free electron laser and free electron laser amplifier using beam transport devices for guiding an electron beam to a wiggler of a free electron laser and returning the electron beam to decelerating cavities disposed adjacent to the accelerating cavities of the free electron laser. Rf energy is extracted from the electron beam after it emerges from the wiggler by means of the decelerating cavities which are closely coupled to the accelerating cavities, or by means of a second bore within a single set of cavities. Rf energy extracted from the decelerated electron beam is used to supplement energy provided by an external source, such as a klystron, to thereby enhance overall efficiency of the system.

It is the primary objective or aim of the present invention to provide an electrically conductive composition for the fabrication of susceptors useful for induction melting of uranium and uranium alloys and to also provide such a composition for forming crucibles and other containment vessels utilized to contain uranium at elevated temperatures. This composition does not appear to interact with molten uranium, since there is no significant reaction between the compositional consituents of the susceptor or containment vessel and the confined uranium. This objective is achieved by utilizing a sintered ceramic composition which consists essentially of about 13-67 vol. % of a refractory metal carbide and a nonconductive oxide selected from a group consisting of zirconium oxide, calcium aluminate, yttria, and combinations thereof.